CARLSBAD, Calif — Chris Pratt never likes to appear overconfident, but even the self-effacing star of NBC's Parks and Recreation has to let loose a little as he steps onto the elevator of the Legoland Hotel.

When the doors close, a disco light starts to spin, and the speakers pump out the maddeningly infectious theme song Everything Is Awesome! from the The Lego Movie (opening Friday nationwide).

Pratt closes his eyes, rolls his neck and belts out the song's main lyric: "Everything is AWESOME!"

And it appears this might literally be true for the 34-year-old actor. In the midst of his TV popularity as Parks and Rec's Andy Dwyer, he's on a roll on the big screen that's worthy of a musical outburst.

Besides voicing "The Special" Emmet in The Lego Movie, Pratt is stepping up to big-ticket projects such as Guardians of the Galaxy, due Aug. 1 from Marvel Studios, and the coveted lead in the dinosaur adventure Jurassic World (2015).

"I do get excited," Pratt says in a more subdued moment. "I need to let my guard down a little bit more."

Pratt acknowledges that he has trained himself to keep his hopes in check "because you break your heart when your expectations are not met. Dude, I'm in these movies. But there's no guarantee that anyone will go see these movies. They can make zero dollars total. It's not hard to lower expectations. It's all about keeping your eyes on the prize and doing good work."

Pratt certainly did that for his earlier movie roles. To portray Oakland Athletics baseball player Scott Hatteberg in 2011's Moneyball, Pratt, who is right-handed, learned how to bat from the left side and practiced the first baseman's signature swing in a batting cage 1,000 times each night.

For his role as a Navy SEAL 2012's Zero Dark Thirty, Pratt worked his body into tiptop shape, even though he wore long-sleeved gear throughout the entire appearance. He then put on 75 pounds to star as the overweight sidekick to Vince Vaughn in the 2013 comedy Delivery Man.

But it was Pratt's inherent innocence that attracted the team behind The Lego Movie.

"Even in real life, he's a guy who is on a very special adventure. The world is about to learn about Chris Pratt," says producer Dan Lin. "But more important, he is just this lovable guy, and that comes across on-screen."

Dealing with starring roles in major projects has required adjustments. On the first day as Peter Quill on Guardians of the Galaxy, Pratt was stunned.

"I walked onto the set. It was like an amusement-park ride. But it was built just for my character," he says. "Millions of dollars spent. That was a moment. Every once in a while, you wipe the fog off and look through the glass and just be astounded. But it quickly fogs back up, and you focus."

Jurassic World is another bewildering experience for him, since Jurassic Park was one of his favorite movies while growing up in Lake Stevens, Wash. Now more than ever, he feels the need to keep his mental balance. "You need to be in a good place. You need to be OK with none of this stuff going well.''

Pratt manages that with a steady home life with actress Anna Faris and their 1½-year-old son, Jack. The rest of his family also keeps him grounded.

"When I start speaking to my brother (Cully) in a certain way, it's like, 'Whoa, back it up, Hollywood. We grew up together. You're the kid I used to fart on,' " Pratt says.

But there's always The Lego Movie theme song, which allows for that brief indulgence in giddiness.

"It does seem to be a fitting song for this point in my life," he says. "We'll see next year. Maybe the song I'm singing next year is 'Everything Was Awesome.' "